Abstract (inglese)

The present Ph.D. thesis concerns the identification and the investigation of biological functions of oligopeptides extracted from the italian PDO Asiago cheese. Using High Performance Liquid Chromatography coupled on electrospray mass spectrometry (HPLC/ESI-MS), several peptides were identified, most of them arose from alfas1- and beta-casein and some of them never previously reported, suggesting a contribution of non starter bacteria enzymes. PCA analysis based on peptide profile allowed to differentiate the cheeses on account of the ripening time and of the use of starter. Therefore, peptides may be used as potential molecular markers as a tool of authenticity of PDO Asiago. The potential antihypertensive activity of Asiago water-soluble extracts (WSEs) was evaluated. Six-months-aged cheeses had a significantly higher inhibitory potency than 12 and 18 months ones and the 3 kDa fraction made a more considerable contribution to the ACE inhibitory activity than 10kDa fraction. Using HPLC/ESI-MS antihypertensive peptides mainly derived from alfas1-casein and beta-casein were identified. The assess of potential antimicrobial activity of WSEs was carried out because the naturally presence of antimicrobial peptides in cheesse may be a useful tool to control the growth of pathogenic bacterial or to determine their death. Six-months-aged cheeses showed higher inhibition against Listeria innocua and slighter higher inhibition against Listeria monocytogenes than 12 or 18 aged cheeses. However, this weak inhibition disappeared after 24 h of incubation suggesting a bacteriostatic activity of Asiago water-soluble peptides. A few antibacterial peptides were identified through HPLC/ESI-MS.